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Using Electron Energy-Loss Spectroscopy (EELS) To Study Rare Earth Elements In Natural Crystals

Published online by Cambridge University Press:  02 July 2020

Huifang Xu*
Affiliation:
Department of Earth and Planetary Sciences The University of New Mexico, Albuquerque, New Mexico, 87131, U. S. A.
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Extract

Because of similar chemical properties of the rare earth elements (Ree), whole series of the Ree may occur in natural Ree-bearing crystals. Relative concentration of the Ree may vary as the crystallization environments change. Electron energy-dispersive spectroscopy (EDS) associated with TEM is unable to resolve Ree and other coexistence elements, such as Ba nd Ti, because of peak overlap and energy resolution (∼ 150 eV) of EDS. Figure A indicate multiple peaks from Ce only. The Cu peaks are from Cu grid holding the specimen. Electron energy-loss spectroscopy (EELS) with energy resolution of < 1 eV is able to resolve all Ree in natural Ree-bearing crystals.

Natural carbonate crystals from a Ree ore deposit were investigated by using EELS associated with field emission-gun (FEG) TEM. The crystals are in a chemical series of BaCO3 - Ree(CO3)F [1]. In Figure B, EEL spectra A and B are from Ce-rich and La-rich bastnaesite (Ree(CO3)F), respectively; spectrum D is from cordylite (BaCO3 (Ree(CO3)F); spectrum E is from huanghoite (BaCO3 Ree(CO3)F), spectrum F is from BaCO3; spectrum C is from an unknown Ree-rich phase.

Type
Electron Energy-Loss Spectroscopy (EELS) and Imaging
Copyright
Copyright © Microscopy Society of America

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References

1. Institute of Geochemistry of Chinese Academy of Science (1988) Geochemistry of Baiyun Obo Ore Deposit. Science Press, Beijing, 556 pp.Google Scholar
2.Xu, H., and Wang, Y. (1999) Oxidative alteration of Ce-rich pyrochlore: HRTEM/EELS investigation. Materials Research Society Symposium Proceedings, Vol. 556, 149156.Google Scholar